I agree with Reef
Ask before sending, don't just rock up with the fish. Pack well, double bag, polybox and heat packs.
I use Post Haste, never had a problem for years then twice within 3 weeks lately the Auckland branch lost my parcel - once coming to me, another when I was sending. Turned up eventually.
NZ Couriers won't ship out of Auckland yet other areas have no problem using them to send up here.
Used Fastways once and it cost me a fortune.